Microclimatic and Diversity Controls on UK Grassland Carbon Cycling

Stott, Heather and Armstrong, Alona and Whitaker, Jeanette and Ostle, Nick (2022) Microclimatic and Diversity Controls on UK Grassland Carbon Cycling. PhD thesis, Lancaster University.

Text (2017HeatherStottPhD)
2017HeatherStottPhD.pdf - Published Version
Download (2MB)

Abstract

The deployment of solar farms in the UK and Europe is accelerating in response to the need to decarbonize energy supplies and the increasing cost competitiveness of photovoltaic (PV) systems. In the UK, solar farms are generally installed on low grade agricultural grasslands. However, UK grasslands are important carbon stores, and the impact of the microclimatic changes induced by the presence of PV arrays, on the myriad of biological, chemical and physical processes which govern carbon cycling and ultimately carbon storage is uncertain. To understand how changes in temperature, soil moisture and solar radiation induced by the presence of PV arrays, affect grassland carbon cycling, these unique spatial and temporal microclimatic changes and their direct and indirect effects on grassland carbon cycling must be disentangled. Using a combination of field and laboratory experiments, this thesis investigates how the microclimatic changes imposed by solar farms affect ecosystem productivity and decomposition processes in temperate grasslands. Results show that the effects of warming and shading on productivity and decomposition processes were determined by the diversity of the vegetation community, with high diversity grassland communities more resistant to warming and shading than low diversity grasslands. Further, we provide some of the first evidence to show how decomposition in temperate grasslands may be affected by changes in solar radiation receipts, with UV-B exposure facilitating subsequent microbial decomposition. Both decomposition and productivity in grassland directly under the PV arrays were suppressed. Further, under PV arrays a greater proportion of biomass was invested as below ground biomass, which is a more stable pool of carbon and more likely to become part of stable carbon stores. Determining the impacts of solar energy farms on grassland carbon cycling could be used to develop management strategies to help maximise the benefits of this renewable energy technology.